The biggest four economies have been extremely stable in international nominal GDP rankings, as compared to those outside the grouping, which tend to swap places almost annually with booms and busts and currency rises and falls. For the "Big Four", there were only 3 major ranking changes in the period from the 1960 to 2015 (55 years), and these one-time changes have been retained. The Big Four economies were, ordered by size, (1960-1990): USA, Soviet Union[1] (not listed in these particular tables), West Germany, and Japan, Japan having passed West Germany in 1967.[2][3] In the 1990s, with the dissolution of the Soviet Union, the Big Four became the Big Three. The last change was the addition and fast rise of China, to which has joined the Big Four since 2008 when it passed Germany,[4] and 2010 when it passed Japan.[3] Excluding the addition of China and the removal of the Soviet Union, the Big Four ranking has remained essentially unchanged since 1967 visavis each other and overall, even accounting for the unification of Germany, Japan's 2 decade long malaise, and throughout the United States' energy shocks, wars, tech bubble, and housing crises. This highly contrasts with nations outside the Big Four grouping, as one can see from the IMF tables below, the nations that occupy the fifth to the fifteenth spots swapping places back and forth, annual rankings having changing every year and had been comparatively very volatile. These include the economies of Russia, Brazil, Canada, Australia, UK, France, Italy, Spain, Mexico and India, all of which are yet again experiencing large revisions in rankings in 2015 (being affected by the strong US dollar).